One gram of the gel was suspended in 2.9 ml of phosphate buffer at pH 7.2. Different sterile media (Bismuth Sulfite Medium, Mannitol salt agar medium, Muller Hinton agar medium, cetrimide agar medium and sabaroud agar medium) were inoculated with the gel, then, incubated for 24 hours. After that, the media were examined to ensure no growth of bacterial genera.